Mailpiece creation systems such as mailpiece inserters are typically used by organizations such as banks, insurance companies, and utility companies to periodically produce a large volume of mailpieces, e.g., monthly billing, or shareholders income/dividend, statements. In many respects, mailpiece inserters are analogous to automated fabrication equipment inasmuch as sheets, inserts and envelopes are conveyed along a feed path, and assembled in various modules of the mailpiece inserter. That is, the various modules work cooperatively to process the sheets until a finished mailpiece is produced.
Typically, inserter systems prepare mail pieces by arranging preprinted sheets of material into a collation, i.e., the content material of the mailpiece, on a transport deck. The collation of preprinted sheets proceed to a chassis module where additional sheets, or inserts, may be added based upon predefined criteria, e.g., an insert sent to addressees in a particular geographic region. From the chassis module, the fully developed collation may continue to a stitcher and/or to a folding module. The stitching module binds an edge or corner of the collation while the folding module folds the content material into panels suitably sized for insertion into a mailpiece envelope.
Notwithstanding the upstream requirements, e.g., operations such as sheet registration, cutting, stitching, or folding, all mailpiece inserters employ an inserter module wherein an envelope is prepared to be filled with content material, e.g., the folded collation, inserts, coupons, etc. In this module, an envelope is conveyed from a side stacker to a transport deck and comes to rest at a series of projecting fingers, also referred to as a “backstop”. The transport deck typically comprises a series of parallel drive belts which are spaced-apart to permit a series of vacuum apertures, disposed between the drive belts, to act along an underside surface of the envelope. That is, the belts are disposed over the top surface of a support plate which dually functions to (i) slideably support the drive belts and (ii) serve as one of the plenum walls through which the vacuum apertures are disposed. With respect to the latter, a series of vacuum channels are disposed along the underside of the support plate and in fluid communication with the vacuum apertures. Therefore, the drive belts convey motion to the mailpiece envelope while the vacuum apertures develop a pressure differential operative to augment the friction forces acting on the envelope by the drive belts.
The fingers of the backstop lie between the drive belts and within elongate slots of the transport deck. Furthermore, the fingers are disposed about a shaft which is rotatable about a transverse axis, i.e., disposed across belts and generally perpendicular to the feed path of the envelope. Moreover, the fingers are affixed to the shaft and project outwardly therefrom, i.e., radially from the axis of the shaft. The shaft is connected to a rotary actuator which is operative to position the fingers from a first position, i.e., parallel to the support plate of the transport deck, to a second position, i.e., orthogonal to the support plate. Consequently, the fingers are rotated into the first position to arrest the motion and register the leading edge of the envelope, and rotated into the second position to permit the passage of the envelope, i.e., after the mailpiece envelope has been filled with content material. More specifically, once the envelope has come to rest along the backstop, other mechanisms, such as one or more suction cups, are employed to open the envelope for filling. That is, the suction cups lift a face sheet of the envelope body upwardly to enlarge the opening of the envelope and facilitate insertion of content material.
While the above described arrangement has proven successful and reliable for conventionally-sized, type-ten (10) envelopes, difficulties have been experienced with respect to larger envelopes. More specifically, difficulties have arisen with respect to envelopes having a larger height dimension, i.e., from the bottom leading edge to the top trailing edge, which can distort, e.g., buckle or bow upwardly, upon striking the backstop of the insertion module. As a result, the system of suction cups, which open the envelope for filling, can be adversely affected by the distortion of the envelope.
While one method to overcome these difficulties may include an increase in vacuum pressure along the underside surface of the envelope, this solution also has limitations. For example, as vacuum pressure increases, there is a commensurate increase in friction forces which develop at the interface between the friction drive belts and the mailpiece envelope. When friction forces reach a threshold level, the friction drive belts will no longer slide relative to the envelope, i.e., slippage along the interface does not occur. As a consequence, mailpiece envelope will tend to fold/buckle upon contact with the backstop of the insertion module.
A need, therefore, exists for an insertion module which eliminates envelope distortion and reliably processes envelopes of variable size.